| 摘要 |
PROBLEM TO BE SOLVED: To cut a fold-back portion extremely readily, safely, and securely despite a simple constitution. SOLUTION: A sheet material fold-back cutting tool 1 is formed at the block- shaped bottom of a cutting tool main body 2 with a guide groove 3 for housing the fold-back portion of a sheet material and guiding the sheet along the fold- back portion. An opposite surface 6 of the guide groove 30 is formed into a downward expanded tapered shape. At the uppermost portion of the guide groove 30, an expanded space 7 is formed in a manner being expanded outward of an extended line of the opposite surface 6. Within the expanded space 7 a cutter 3 having a blade 4 at its front is disposed in the form of a blade tip vertically projected in the guide groove 30 by only a projection length of (h). The blade 4 of the cutter 3 is so located at a rake angle ofθ1 that the blade tip can advance more than the root.
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